Slide valves are well known in the art for the control of gases and liquids. Some slide valves are hand operated while others are mechanically driven. An example of a conventional slide valve may be found in U.S. Pat. No. 5,039,063 to Louch, et al and assigned to the Marathon Oil Company. Such valves are an inexpensive means of controlling fluid flow. In the slide valve of '063 patent the inventors are concerned with a smooth interior bore that will prevent any turbulence in the flow. This '063 valve was intended for laboratory usage and is unlikely to be used in high pressure applications.
Where slide valves are used commercially they can be used for low and moderate pressure gases and liquids. These types of devices have been limited in their applicability for a number of reasons. An important problem is that these valves become unsuitable or lock up at high pressures so that they can not be operated easily. Further, due to the high pressures, they can suffer from damage to sealing o-rings positioned adjacent to the moveable valve assembly. Because of problems such as these slide valves are generally limited to operating fluid pressure of 250 psig or below.
Another problem is that vibration, operator error or other problems can sometimes result in an inadvertent movement of the valve control.